CDC reports COVID-19 case counts, deaths, and laboratory testing numbers daily online. Data on the COVID-19 website and CDC’s COVID Data Tracker are based on the most recent numbers reported by states, territories, and other jurisdictions. Data are dependent on jurisdictions’ timely and accurate reporting.
In addition, CDC regularly reports provisional death certificate data on the NCHS website. Reporting the number of deaths by using death certificates ultimately provides more complete information but is a longer process and, therefore, these numbers will be less than the deaths count on the COVID-19 website.
CDC tracks COVID-19 illnesses, hospitalizations, and deaths to monitor trends, detect where outbreaks are occurring, and determine whether public health measures are working. However, counting exact numbers of COVID-19 cases is not possible because COVID-19 can cause mild illness, symptoms might not appear immediately, there are delays in reporting and testing, not everyone who is infected gets tested or seeks medical care, and there are differences in how completely states and territories report their cases.
COVID-19 is one of about 120 diseases or conditions health departments voluntarily report to CDC. State, local, and territorial public health departments verify and report cases to CDC. When there are differences between numbers of cases reported by CDC versus by health departments, data reported by health departments should be considered the most up to date. Health departments may update case data over time when they receive more complete and accurate information. The number of new cases reported each day fluctuates. There is generally less reporting on the weekends and holidays.
CDC reports death data on three sections of the website: U.S. Cases & Deaths, COVID Data Tracker, and NCHS Provisional Death Counts. U.S. Cases and COVID Data Tracker get their information from the same source (total case counts); however, NCHS Death Counts are based on death certificates that use information reported by physicians, medical examiners, or coroners in the cause-of-death section of each certificate. Data from each of these pages are considered provisional (not complete and pending verification) and are therefore subject to change. Counts from previous weeks are continually revised as more records are received and processed. Because not all jurisdictions report counts daily, counts may increase at different intervals.
As of April 14, 2020, CDC case counts and death counts include both confirmed and probable cases and deaths. This change was made to reflect an interim COVID-19 position statementpdf iconexternal icon issued by the Council for State and Territorial Epidemiologists on April 5, 2020. The position statement included a case definition and made COVID-19 a nationally notifiable disease. Nationally notifiable disease cases are voluntarily reported to CDC by jurisdictions.
A confirmed case or death is defined by meeting confirmatory laboratory evidence for COVID-19.
A probable case or death is defined by one of the following:
- Meeting clinical criteria AND epidemiologic evidence with no confirmatory laboratory testing performed for COVID-19
- Meeting presumptive laboratory evidence AND either clinical criteria OR epidemiologic evidence
- Meeting vital records criteria with no confirmatory laboratory testing performed for COVID19
Not all jurisdictions report probable cases and deaths to CDC. When not available to CDC, it is noted as N/A. Please note that jurisdictions may reclassify probable cases at any time to confirmed cases (if confirmatory laboratory evidence is obtained) or withdraw probable case reports entirely if further public health investigation determines that the individual most likely did not have COVID-19. As a result, probable case counts can fluctuate substantially. A jurisdiction might even report a negative number of probable cases on a given day, if more probable cases were disproven than were initially reported on that day.
There are currently 60 U.S.-affiliated jurisdictions reporting cases of COVID-19. This includes the 50 states; the District of Columbia; New York City, the U.S. territories of American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, Puerto Rico, and the U.S Virgin Islands; and three independent countries in compacts of free association with the United States (Federated States of Micronesia, Republic of the Marshall Islands, and Republic of Palau). New York State’s reported case and death counts do not include New York City’s counts as they separately report nationally notifiable conditions to CDC.